Container with infolded bottom closure



Feb- 4, 1964 H. B. EGLEsToN ETAL 3,120,335

CONTAINER wTTH TNFOLDED BOTTOM cLosuRE 4 Sheets-Sheet l Filed Sept. 7,1961 Feb. 4, 1964 H. B. EGLEsToN ETAL 3,120,335

CONTAINER WITH INFOLDED BOTTOM CLOSURE Filed Sept. 7, 1961 4Sheets-Sheet 2 Feb. 4, 1964 H. B. EGLEsToN ETAL 3,120,335

` CONTAINER WITH INFOLDED BOTTOM cLOsURE Filed Sept. '7, 1961 4Sheets-Sheet 3 INVENTORS CMR/.5 Z MoN/Q05 w #44, 4MM am @WW ATTORNEYSFeb. 4, 1964 H. B. EGLEsToN ETAL 3,120,335

CONTAINER WITH INFOLDED BOTTOM CLOSURE 4 Sheets-Sheet 4 Filed Sept. 7,1961 United States Patent 3,120,335 CONTAINER WITH INFOLDED BOTTOMCLOSURE Harry B. Egleston, Livonia, and Charles Z. Monroe, Detroit,Mich., assignors to Ex-Cell-O Corporation, Detroit, Mich., a corporationof Michigan Filed Sept. 7, 1961, Ser. No. 136,505 Claims. (Cl. 229-43)The present invention relates to packaging and more specifically to acontainer bottom closure construction. The invention nds particular, butby no means exclusive, utility in disposable containers adapted fordistribution of milk and other dairy products.

This application is a continuation-in-part of our copending U.S.application Serial No. 707,259, filed January 6, 1958, now abandoned.

One form of container of the type just noted and presently in lwidecommercial use is disclosed in U.S. Patent No. 2,750,095, issued June12, 1956, on the application of Carroll R. Alden (Reissue No. 25,021,issued August 8, 1961). Such a container is customarily erected from aiiat blank formed of sheet stock suc-h as paperboard which has 'been cutto shape and impressed with an appropriate pattern of score lines. Theselines define a plurality of side panels together with correspondingupper and lower extension aps or closure members.

The usual procedure in erecting the container is to form the blank intoa polygonal tube open at both ends and then to close the lower or'bottom panel extensions, retaining them in place by means of a suitableadhesive. It is presently the practice to coat or impre'gnate theexposed surfaces of the erected tube |by lirnrnersing it in a bath ofmolten paraffin. Following this operation, the container is cooled toharden the paraiin and is then filled with a selected product such yasmilk. The container top is closed and sealed by pressing the closureelements together with heated jaws, thereby yfusing the paraiiin coatingso that all cracks are sealed. In order to supplement the strength ofthe paraffin bond, the top closure elements may be stapled together.

Although paraffin coated containers of the above-described type havebeen commercially successful, there are certain disadvantages inherentin their use, one of the most marked of which involves the paraincoating. In the first place, a suitable dip tank of molten paraffin mustbe maintained as part of the packaging machinery at the dairy orprocessing plant. This, along with the extra care and attention requiredon the part of the operator, plays a part in increasing the cost of thecontainer and finally of the ultimate product. Also, under certainextreme conditions, globules of the parain coating may Hake off of thecontainer walls. While this does not impair the sanitary integrity ofthe contents, it does tend to impair consumer acceptance of thecontainer.

It has now been discovered that paperboard of the quality heretoforeused for dairy product containers can be economically coated with heatand pressure sensitive thermoplastic substances. The thermoplasticsubstance used is desirably one which is inert to the substances to bepackaged, is strong and durable, is inexpensive, and is easy to apply insheet form onto the paperboard. A coating of' this sort renders thepaper sheet material resistant to fluids which would be packaged in thecontainer including such acidic products as milk. One example of such athermoplastic substance which is useful for packaging dairy products ispolyethylene. It will be apparent to those skilled in the art, however,that other thermoplastic materials, such as polyvinyl chloride,polyvinylidene chloride, polyvinyl chloride and acetate copolymer, andpolypropylene, to name only a few, will find use under favorablecircumstances.

'3,120,335 Patented Feb. 4, 1964 ICC Paper sheet stock for formingcontainers is initially supplied in the form of rolls, and as the stockis produced it can be coated on both sides with a layer of polyethylenethermoplastic material. One method of accomplishing this is by heatingand stretching the polyethylene and applying it when hot directly ontothe surface of the paper to which it becomes tightly bonded. The surfaceof the paper to be used for the outside of the blank is generally coatedwith a layer approximately 3A of a mil thick while the inside surface ofthe sheet -is coated with a layer of polyethylene approximately 1 to11/2 mils thick.

The general aim of the present invention is to provide a new andimproved container formed of thermoplastic sheet material, orthermoplastic-coated paperboard sheet material, and which will bestrong, simple to erect, close and seal, and susceptible of high volumeeconomical production for packaging milk and other comestibles.

A more specific object of the present invention is to provide acontainer of the above type having surfaces of sanitary heat andpressure sensitive thermoplastic material which not only protects thecontents of the container against admission of harmful substances butalso serves as a sealing adhesive for effecting tight closure andsealing of the container.

Another object of the invention is to provide an improved container ofthe character set forth and having a bottom closure susceptible ofautomat-ic closing and sealing to form a strong leak-proof bottom on thecontainer which will remain Huid-tight even under severe conditions ofuse, such as being dropped on a bottom corner.

Still another object of the invention is to provide a container of theforegoing type and having a bottom closure with at least three plies ofintegrally connected stock at each bottom corner area and a minimallength of raw edge exposed to the interior of the container and thecontents thereof.

Other objects and advantages of the present invention will becomeapparent as the following description proceeds, taken in connection withthe accompanying drawings, wherein:

FIGURE 1 is a perspective view of an illustrative closed and sealedcontainer embodying the present invention.

FIG. 2 is a layout View of a 'blank from which the container in FIGURE 1was erected and showing the inside surface thereof.

FIGS. 3, 4, 5 and l6 are fragmentary perspective views illustratingsequentially various steps in forming the bottom closure of thecontainer of FIGURE l.

FIGS. 7, 8, 9 and 10 are fragmentary perspective views similar to FIGS.3 to 6 but showing another form of container 'bottom closure alsoembodying the invention.

FIG. 11 is a layout view of the inside face of a blank similar to thatshown in FIG. 2 Ibut yadapted to define the bottom closure of FIGS. 7 to'10.

FIG. 12 is an outside ybottom View of the container of FIGURE 1 andshowing certain embossing of the latter in accordance with a furtheraspect of the invention.

FIG. 13 is an outside bottom view similar to FIG. 12 but showing acontainer having the bottom closure of FIGS. 7 to l0.

FIG. 14 is a view of the inside face of the container bottom of FIG. 13,looking in the direction indicated by the line 14-14 in FIG. 10.

While 'the invention is susceptible of Various modifications andalternative constructions, certain illustrative containers have beenshown in the drawings and will be described -below in detail. 4It shouldbe understood, however, that there is no intention to limit theinvention to the specific forms disclosed. On the contrary, theinteniton is to cover all modifications, alternative constructions,equivalents and uses falling within the spirit and scope of theinvention as expressed in the appended claims.

Referring more specifically to the drawings, there is shown a container(FIG. 1) which represents an illustrative embodiment of the presentinvention, The container 20 is formed from paper or other suitable sheetmaterial and is self-sustaining in shape. To render the sheet materialuiddtight and capable of holding such acidic liquids as milk, the sheetmaterial has surfaces of, or is coated with, a thermoplastic material ofthe type exemplified by polyethylene.

The container 20 comprises a tubular body 21 which in the presentinstance happens to be substantially square in cross section. At itsbase the body 21 is provided with a bottom closure 22. The upper end ofthe body 21 in this instance terminates in what will be recognized asthe familiar gable top type of end closure 23 which is surmounted by acentral laminar rib or truss 24. The top end closure has incorporatedtherein an extensible spout for dispensing the contents of thecontainer.

The container 20 is fashioned from a tlat blank 25 of high-gradepaperboard coated with a layer of polyethylene thermoplastic material.By means of an appropriate pattern of score lines the blank 25 (theinner face of which is illustrated in FIG. 2) is divided into aplurality of panels and areas which are utilized for the walls of thecontainer and the closure parts when the container is erected. Thecentral and major area of the blank becomes the body 21 of the containerand is defined by spaced apart transverse score lines 26, 28, running insubstantially parallel relation across the face of the blank.Intersecting the lines 26, 28, at spaced intervals therealong are aseries of perpendicular score lines 29, 30, 31, and 32, which define, inthe central and major area of the blank, side panels 34, 35, 36, and 37together with a fractional side panel or side seam tlap 38. When thecontainer is erected, the latter is adhesively secured in overlyingrelation with the inside face of the side panel 34.

It should be noted that the transverse score lines 26, 28 are notcontinuous but are formed in staggered portions -interrupted by theperpendicular score lines 29, 30, 31, and 32. The purpose of thisstaggered sco-ring is to accommodate the thickness of the paper as it isbent along the score lines when the container is erected and thusprevent crowding of the paper at the various corner junctions of thescore lines. This not only enhances the strength and appearance of theiinished container but facilitates its erection and closure by automaticmachinery.

Connected to the lower edges of the side panels along the lowertransverse score line 28 are bot-tom closure panels 39, 40, 41, and 42.Accordingly, alternate side panels 34, 36 have respectively connectedtherewith opposed bottom closure panels 39, 41. 'Ihe latter in turninclude respectively a tuck-in flap 5t) and an overlying or outsideoverlap flap 51. The tuck-in flap Sti is relieved or recessed at 52 sothat it receives the adjacent end 53 of the side seam tiap when thebottom closure is sealed.

In this manner an extra thickness of sheet material at one edge of thebottom closure is avoided.

Similarly, alternate side panels 3,5, 37 have connected therewith alongthe transverse score line 28, opposed triangular infold panels 40, 42,respectively. The infold panel 40 is anked by triangular fold-backpanels 55, 56 connected thereto along converging score lines 5S, S9,starting at the intersections between the perpendicular score lines 29,and the transverse score line 28, converging downwardly and intersectingat the cut lower edge of the blank (as viewed in FIG. 2,). By the sametoken, infold panel 42 is flanked by fold-back panels 6), 61 connectedthereto along fold lines 62, 63. In addition to the above connections,triangular fold-back panel 56 is connected to bottom panel 39, panel 55is connected to bottom panel 41, panel 61 is connected to panel 41,while panel 60 is connected to the bottom portion 53 of the side seam ap38.

Integral with the upper ends of the side panels, but separated therefromby the transverse score line 26, are a plurality of panel extensionswhich give the top of the container 2t) its characteristic gable shape.These areas include a transverse score line 66 generally parallel to thescore line 26 and spaced between the latter and the top edge of theblank 25. The areas below the line 66 define roof panels 68, 69 andtriangular end and fold-back panels 75, 78, 79 and 76, `B8, 89 of thetop closure. The areas above the line 66 define the parts of the centrallaminar rib 24, namely, inner rib panels S4, 85, 94, 95, outer ribpanels 70, 71, and sealing iiaps 72, 73. Again score line 66 is not astraight line but includes staggered portions 66a, 66b, 66e and 66dcorresponding respectively to the panels 34, 35, 36 and 37, foraccommodating the thickness of the paper when the container closure isfolded.

The blank 25 is transformed into a completed container as illustrated inFIG 1, by iirst folding it upon itself to form a fiat tube andadhesively securing the side seam ap 38 and its extensions 53, 98, 99 tothe inside faces of panels 39, 34, 78 and 84. While it is possible toutilize the polyethylene coating as an adhesive for the side seam, itmay in some instances be feasible to apply an additional amount ofadhesive thereto for purposes of forming the side seam. Such addedadhesive is desirably resistant to heat at the melting point of thepolyethylene or other coating on the container so that the side seamremains tight during subsequent closing and sealing operations. Onepolyethylene base adhesive used for the side seam has a melting point ofabout 500 F.

The iiattened blank tube is then erected into a tube of substantiallysquare cross section (FIG. 3) and the bottom closure is completed.Accordingly, the score l-ines or creases 58, 59, 62, and 63 are brokenor given a prebend by folding the triangular infold aps 40, 42 inwardlytowards each other (FIG. 4). The tuck-in tiap 5) is then in position forinsertion beneath end panel 39 and above the triangular fold-back aps 56and 60 so that the bottom panel 39, which includes the sealing iiap 51,overlies end panel 411, which includes the tuck-in ap (as Viewed in FIG.5).

In order to seal the bottom of the container the bottom closure panelsare first broken but before they are finally folded they are subjectedto a source of intense heat so as to melt or vat least activate andrender adhesively active the coating of polyethylene on both surfaces ofthe bottom closure panels. When a polyethylene coating is used the heatmust be suflicient to partially melt the coating which melts betweenabout 230 and 275 F., depending upon its density. These panels are thenfolded together and the tuck-in flap 50 is inserted in place. When thebottom closure is completed it is subjected to pressure between cooledpressure pads to cool and solidify the polyethylene plastic adhesive andthus produce a completely sealed bottom end closure.

Provision is made for obtaining an exceptionally tight seal of thebottom closure 22 when finally completed. .VI his is accomplished inlarge measure by constructing the bottom closure parts so that the cutedges of the triangular foldback pane-ls 5S, 56, 60 and 61, which abuteach other in the completed bottom closure, will enter into positiveabutting engagement with each other prior to completion of the bottomclosure. In furtherance of such objective, the bottom closure panels 4Gand 42 are so proportioned that the combined length of the triangullarfold-back panels 55, S6, as well as the combined length of thetriangular fold-back panels 60, 61, normal to the score line 28, will beslightly greater than the base width of each triangular bottom closurepanel measured along the score line 2S (IFIG. 2). Stated another way,and in the present instance, the bottom closure panels are proportionedso that those portions of the vertical score lines 29, 30, 31 and 32,joining the bottom closure panels 39, 4i), 41 and 42, and defining aside of each of the triangular foldback panels, are slighlty longer thanone-half the width of each triangular bottom closure panel measuredalong the score line 28. Thus, as the bottom closure panels are foldedinfto engagement and approach the position illustrated in PIG. 5, thecut edges of thc triangular fold-back panels 55, 56, 6!) and 61 willenter into positive abutting engagement with each other. With furtherdownfolding of the bottom closure panels from the position of `FIG. 5 tothe fully downfolded position shown in FIG. 6, and the application ofsealing pressure thereto in the latter position, the paperboard iscrowded together under substantial compression in its own plane las wellas transversely thereof. tThe tightness of the ultimate bottom seal isthus materially increased.

When the container has been erected and the bottom closure sealed, it isnormally in a sanitary condition. In some instances, however, it may besubjected to iurther sterilization as by irradiation with ultravioletlight or by dipping in a tank of water at approximately 200 F Thesterilized containers are then filled with the desired product.

To seal the container top closure, the parts thereof are iniolded intogable form. During the course of such action the triangular panel creaselines 86, 81, 90, 9'1 are broken by infolding the triangular end panels75, 76 toward each other. The inner and outer rib panels and Sealingliaps 72, 73 are then heated on both sides, as was done with the bottomflaps, to adhesively activate the polyethylene thermoplastic coating.The container is then closed `as by passing its top portion between apair of converging shoes which bring the adhesively activated rib panelsand sealing flaps together to complete the gable top structure. The ribpanels and sealing iiaps are thereupon subjected to substantial sealingpressure which may be derived from cooled pressure jaws leaving the topclosure in sealed condition as illustrated in FIG. 1. The top closureseal may, of course, be broken by `the user through deliberateapplication of external forces to effect partial disassembly of the toprib 24 and expose the pouring spout housed therein.

l.For the purpose of further enhancing the fluid-tight integrity and thedurability of the seal in both the bottom and top closures of thecontainer 20, an additional precaution may be taken, particularly wherethe container is used for packaging fluids. This. involves theapplication of increased pressure to selected areas of the closure partsduring the pressure sealing operation, producing indentations orembossments in the closure plies which effectively close up incipientfluid escape channels. In the present instance, these areas of increasedpressure or ernbossing on'the bottom closure are represented by thecrosshatched areas in FIG. 12.

AReferring more specifically to IFIG. 12, the outside bottom View of thecontainer 2t) is there shown. Rectangular embossed area 105 on overlyingor outside bottom panel 39 has been pressed inwardly forl almost thethickness of one ply of stock. This effectively blocks the incipicntleakage channels which would otherwise occur along the free-cut edge ofthe bottom tuck-in flap 5? and the side seam lflap 53. Embossrnents 106,which in this instance happen to be circular, are located primarily onthe overlying or outside bottom panel 39 and are adapted to block oichannels at the abutting edges of bottom foldback panels 55, 56, 60, 61.In addition, the embossments 106 enhance the sealing between the bottomfold-back panels and the flaps `5t?, 51, 53, on the one hand, andbetween the bottom fold-back panels and the bottom infold panels 40, 42,on the other hand. Similarly, embossments 108, which.v happen to bewedge-shaped, are situated adjacent the lateral edges of the overlyingbottom flap 51` and close the incipient channels between the underlyingabutting plies of the bottom tuck-in flap 56, side seam ap 53, and thepanels 40', 55, 56, and 42, 60, 61.

The container may have another form of bottom closure 22a dilering insome respects from the bottom closure 22 described above but alsoembodying the present invention. Turning now to FIGS. 7 to 11,inclusive, 13 and 14, wherein like reference numenals designate likeparts described earlier herein, it lwill be noted that rthe bottomclos-ure 22a bears considerable similarity to the bottoni closure 22.

In this instance, the container 20 is formed from a flat blank 110, theinside face of which is shown in IFIG. 11, having many parts in commonwith the blank 25 shown in FIG. 2 and already described herein. Theblank thus includes transverse score lines 26, 28, 66, perpendicularscore lines 29, 30, 31 and 32, side panels 34, 35, 36, 37, and side seamilap 38. Above the score line 26, the blank includes a series of topclosure elements which in this instance happen to be similar to those ofthe blank 25. Below the score line 28, the blank 110 includes triangularbottom closure panel 40 ilanked by triangular fold-back panels 55, 56,all constituting an eX- tension of the side panel 35, and triangularbottom closure panel 42 and fold-back panels 60, 61, all being anextension of side panel 37. Alternating with the panels 40 and 42, aremajor bottom closure panel l'111, constituting an extension of the sidepanel 34, and bottom closure panel 112, constituting an extension of theside panel 36. In addition, there is panel extension 114 of the sideseam flap 38.

In the bottom closure 22a, the major bottom panels '111, 112 foldrelative to one another in a relationship which is just the oppositefrom that of their counterparts 39 and l41 in the closure 22. Thus, thefree-cut marginal edge portion of panel 111 has defined thereon atuck-in iiap 2115, while the free-cut marginal edge portion of the panel112 has defined thereon an overlying or outside overlap iiapl 116. Theends of the tuck-in flap are chamfered or tapered as at 118 tofacilitate entry of the ap 115 between the triangular fold-back panels55, 61 and the inside face of the overlying flap `11'6 of bottom panelv112. In addition?, the end of Ithe side seam panel extension 114 isrelieved or chamfered as at 119, while the end portion of the overlyinglflap 116 which faces it is also relieved or chamfered at 120.

Completion of the formation of the bottom closure 22a is similar to thatof the closure 22 and is illustrated sequentially :in FIGS. 7, 8, `9 andl0. Starting with the blank v11i) in open-ended tubular lforfrn,illustrated in FIG. 7, the triangular bottom panels liti, 42 and theirassociated lfold-back panels 55, 56, `60, 61, as Well as major bottompanels 111, 112 are first broken inwardly and downwardly, as illustratedin FIG. 8. They are then subjected to `fairly intense heat, as mentionedearlier herein, so as to render a-dhesively lactive the plasticmaterial, such as polyethylene, on both surfaces of the bottom closurepanels. The iniolding o-r downiolding is then contin-ued rapidly, thetuck-in -flap 115 being rst slid beneath the inside lface of theoverlying ap 116 and thereupon inserted between the inside face of theoverlying botto-m panelv 112 and adjacent triangular |fold-back panels55, 61. Prior to the completion of the downfolding, with the bottomclosure in the 4condition illustrated in FIG. 9', the ap 116substantially overlies the tuck-in flap 115. Due to the fact that thetriangular fold-back panels 55, 56, '60, 61 are constructed with thesame length-to-side panel-width relationship described in connectionwith the bottom yclosure 22, the ends of the fold-back panels enter intopositive abutting engagement prior to completion of downioldin-g. The-downfolding conti-nues with crowding of paperboard stock at theabutting cut ends of the Ifol-dback panels, until the bottom closurey22a has reached the :condition illustrated in JFIG. 10l at which timethe ultitmate seal is completed.

For the purpose of further enhancing the seal of the bottom closure 22aand eliminating incipient leakage channels Iwhich might otherwise occur,resort may be had to a plurality of concentrated pressure areas definingblocking embossments similar to those described above in connection withthe bottom closure 22. Accordingly, it will be noted upon reference toFIG. 13, which is an outside view of the bottom `closure 22a, that thesame includes a relatively large rectangular embossment 121 (shown indot-dash outline) covering the overlying or outside bottom lap 112except the area thereof overlying the tuckin flap. By the same token,the inner major bottom panel 111 is embossed over a rectangular area 122extending from the side seam panel to the edge of the overlying ilap115. In addition, spot embossments 124 (FIGS. 13 and 14), which in thisinstance happen to be of circular shape with narrow rectangular centralindentations, block incipient leakage channels adjacent the free-cutedge of the tuck-in ap, and also adjacent the inside free-cut edge andthe chamfered end 119 of the side seam panel extension 114. lCertain ofthese incipient leakage channels run between the outer perimeter of thecontainer and the central portion of the free cut edge of the bottomclosure panel 115 which is exposed to the interior of the container.Another such incipient leakage channel runs from the exposed portion ofthe edge of the side seam panel extension 114 inside the container,along such edge and the end of the side seam panel extension, to theouter perimeter of the container (FIGS. 13 and 14). By reason of thechamfers 119, 120 and the selective distribution of sealing pressureupon the bottom closure 22a, the overlapping plies of the side seamextension 114 and the inside panel 11-1, as wel las the overlappingplies of the tuckin flap 115 and overlying flap 116 become substantiallycoplanar, eliminating objectionable bulges on the outer surface of thebottom closure.

We claim as our invention:

l. A container of paperboard or the like having an overall surface ofthermoplastic material that becomes adhesive when subjected to heat,said container comprising, in combination, a tubular body, a top closureoverlying said body, tirst and second pairs of opposed bottom closurepanels connected to said body, said second pair of bottom closure panelsbeing triangular in shape and infolded ybetween said body `and saidfirst pair of bottom closure panels, two pairs of triangular Ifold-backpanels each pair of which is connected to a respective one of saidtriangular bottom panels and to respective ones of said first pair ofopposed bottom closure panels, said foldback panels also having cutedges and being folded against the inside surface of said first pair ofopposed bottom panels, the combined length of said fold-back panelsalong said opposed bottom panels of said tirst pair being greater thanthe length of the base of the adjoining triangular bottom panel wherebysaid fold-back panels are crowded together along their cut edges uponinfolding and sealing of said bottom closure panels.

2. A container of paperboard or the like having a surface ofthermoplastic material that becomes activated adhesively when subjectedto heat, said container comprising, in combination, a tubular body, atop closure overlying said body, a first pair of opposed bottom closurepanels connected to said body, a second pair of opposed bottom closurepanels also connected to said body, said second pair of bottom closurepanels being triangular in shape and infolded between said body and saidrst pair of bottom closure panels, two pairs of triangular fold-backpanels each pair of which is connected to a respective one of saidtriangular bottom panels and to respective ones of said iirst pair ofopposed bottom closure panels, said fold-back panels also having cutedges and being folded against the inside surface of said first pair ofopposed bottom panels and with adjacent edges of each said pair ofyfold-back panels abutting each other, the combined length of saidfold-back panels along said opposed bottom panels of said first pairbeing greater than the length of the base of the adjoining7 triangularbottom panel whereby said fold-back panels are abuttingly crowdedtogether along their cut edges upon infolding and sealing of said bottomclosure panels, and an overlying ilap integral with one of said rst pairof bottom closure panels and adapted to extend over the other bottomclosure panel in said lirst pair beyond the abutting edges of saidfoldback panels.

3. A container of paperboard or the like having an overall surface ofthermoplastic material that becomes activated adhesively when subjectedto heat, said container comprising, in combination, a body, a topclosure on said body, iirst and second pairs of opposed bottom closurepanels connected to said body, said second pair of bottom closure panelsbeing triangular in shape and in- -folded between said body and saidfirst pair of bottom closure panels, two pairs of triangular fold-backpanels each pair of which is connected to a respective one of saidtriangular bottom panels and to respective ones of said iirst pair ofopposed bottom closure panels, said fold-back panels also having cutedges and being folded against the inside surface of said iirst pair ofopposed bottom closure panels and with adjacent cut edges of each saidpair of fold-back panels abutting each other, the combined length ofsaid `fold-back panels along each said opposed bottom closure panel ofsaid rst pair being greater than the length of the base of the adjoiningtriangular bottom panel whereby said abutting cut edges of saidfold-back panels are crowded together upon infolding and sealing ot saidbottom panels, a tuck-in flap integral with one of said rst pair ofbottom closure panels and inserted between the other bottom closurepanel or said first pair and the fold-back panels thereagainst, and anoverlying flap integral with and extending over the other one of saidfirst -pair of bottom closure panels, said overlying flap extending overand beyond said tuck-in flap.

4. A container of paperboard or the like having an overall surface lofthermoplastic material that becomes activated adhesively when subjectedto heat, said container comprising the combination of a tubular bodyhaving a side seam flap, a top closure on said body, iirst and secondpairs of opposed bottom closure panels connected to said body, a sideseam panel extension secured to one of said tirst pair of bottom closurepanels, a relieved end portion on said side seam panel extension, saidsecond pair of bottom closure panels being triangular in shape andinfolded between said body and said irst pair of bottom closure panels,two pairs of triangular fold-back panels each pair of which is connectedto a respective one of said triangular bottom panels and to respectiveones of said tirst pair of opposed bottom closure panels, said fold-backpanels being folded against the inside surface of said first pair ofopposed bottom panels and with adjacent edges of each said pair offold-back panels abutting each other tightly throughout their entirelength, and an overlying fiap integral with the other one of said iirstpair of bottom closure panels, said overlying ilap being constructed andarranged to extend over the first one of said first pair of bottomclosure panels and beyond the abutting edges of said fold-back panels toeffect a thermoplastically scaled margin between said abutting edges andthe exterior of said container, said overlying lflap having a relievedportion substantially complemental to said relieved end portion of saidside seam panel extension.

5. A blank for a container of foldable sheet material having an overallsurface of thermoplastic material that becomes adhesive when subjectedto heat, said blank comprising, in combination, a plurality of sidepanels, a plurality of top closure panels, first and second pairs ofbottom closure panels alternately connected to said side panels asextensions thereof, said second pair of bottom closure panels beingtriangular in shape, two pairs of triangular fold-back panels each pairof which is connected to a respective one of said triangular bottompanels and to respective ones of said first pair of opposed bottemclosure panels, each said pair of told-back panels having a common freecut edge, the combined length of said fold-back panels along said bottomclosure panels of said lirst pair being greater than the length of thebase of the adjoining triangular bottom panel whereby said fold-backpanels are adapted to be crowded together along their free cut edgesupon infolding and sealing yof said bottom closure panels.

6. A container of paperboard or the like having an overall surface ofthermoplastic material that becomes activated adhesively when subjectedto heat, said container comprising the combination of a tubular body, atop closure Ioverlying said body, iirst and second pairs of overlappingopposed bottom closure panels connected to said body, said second pairof bottom closure panels being tliangular in shape and infolded betweensaid body and said iirst pair of bottom `closure panels, two pairs oftriangular told-back panels each pair of which is connected to arespective one of said triangular bottom panels, said fold-back panelsbeing folded against the inside surface of said rst pair of opposed`bottom panels and With adjacent edges of each said pair of fold-backpanels abutting each other, an overlap iiap integral with one of saidiirst pair of bottom closure panels, the other bottom closure panel ofsaid `first pair having an overlapped edge with its central portionexposed to the interior of the container, said overlap flap beingconstructed and arranged to extend over the other bottom closure panelof said first pair and beyond the abutting edges of said fold-backpanels, and means defining blocking indentations in at least said one ofsaid iirst pair of bottom closure panels adjacent said overlapped edgeof said other bottom closure panel between the central portion of saidedge and the outer perimeter of said container, whereby incipientleakage channels are blocked and the iiuidtight integrity of saidcontainer is maintained.

7. A container of paperboard or the like having an overall surface lofthermoplastic material adapted to become activated adhesively whensubjected to heat, said container comprising, in combination, a tubularbody, a top closure on said body, iirst and second pairs of overlappingopposed bottom closure panels connected to said body, a side seam panelextension secured to one of said irst pair of bottom closure panels,said side seam panel extension having an end portion and an inner edge,said inner edge having a portion exposed to the inte-rior of thecontainer, said second pair of bottom closure panels being triangular inshape and infolded between said body and said rst pair of bottom closurepanels, two pairs of triangular fold-back panels each pair of which isconnected to a respective one of said triangular bottom panels, saidfold-back panels being folded :against the inside surface of said iirstpair of opposed bottom panels and with adjacent edges of each said pairof fold-back panels abutting each other, the other bottom closure panelof said rst pair having an overlapped edge with its central portionexposed to the interior of the container, indentations in at least saidone of said means defining blocking rst pair of overlapping opposedbottom closure panels adjacent said overlapped edge between the centralportion thereof and the outer perimeter of the container, and meansdeiining blocking indentations in at lea-st one of said first pair ofbottom closure panels between said exposed portion of said inner edge oisaid side seam panel extension and the outer perimeter of saidcontainer.

8. A container of oldable sheet material having a thermoplastic surfacethat becomes activated adhesively when subjected to heat, said containercomprisin in combination, a body, a top closure on said body, iirst andsecond pairs of opposed bottom closure panels connected to said body, aside seam panel extension secured to one of said tirst pair of bottomclosure panels and having an inner edge and a projecting end, saidsecond pair of bottom closure panels lbeing triangular in shape andinfolded between said body and said iirst pair of bottom `closurepanels, two pairs of triangular fold-back panels each pair of which isconnected to a respective one of said triangular bottom panels, saidfold-back panels being lfolded against t-he inside surface of said irstpair of opposed bottom closure panels and with adjacent edges of eachsaid pair of fold-back panels abutting each other, a tuck-in iiapintegral with one of said iirst pair of bottom closure panels andinserted between the other bottom closure panel of said rst pair landthe fold-back panels thereagainst, said tuck-in flap having anoverlapped edge, an overlap flap integral with and extending over theother one of said iirst pair of bottom closure panels, said overlap iiapextending over and beyond Isaid tuck-in iiap, said overlap iiap having arelieved portion substantially complemental to said projecting end ofsaid side seam panel extension, and means defining blocking indentationsin said rst pair of bottom closure panels at the overlapped edge of saidtuck-in flap and at said inner edge and projecting end of said side seampanel extension.

9. A blank for a container as defined in claim 5, having an overlappingflap integral with one of said iirst pair of bottom closure panels.

10. A blank for a container `as defined in claim 5, having a tuck-in apintegral with one of said iirst pair of bottom closure panels.

References Cited in the tile of this patent UNITED STATES PATENTS1,924,529 Wellman Aug. 29, 1933 2,189,431 Moore Feb. 6, 1940 2,324,757Bedey July 20, 1943 2,362,862 Sidebotham Nov. `14, 1944 2,461,251 BalllFeb. 8, 1949 2,501,852 Ringler Mar. 28, 1950 FOREIGN PATENTS 676,531Great Britain July 30, 1952 UNITED STATES PATENT OFFICE CERTIFICATE 0ECORRECTION Patent Noo 3y 120335 February 4V 1964 Harry Bo Egleston etal.7

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should resid asCorrected below.

Column 9q line 52 after "Container," insert means defining blocking line53 strike out "means definingm; line 54, strike out "blocking"a Signedand sealed. this 23rd day of June 1964e (SEAL) Attest:

ERNEST WQ SWIDER EDWARD J. BRENNER Atesting Officer Commissioner ofPatents

1. A CONTAINER OF PAPERBOARD OR THE LIKE HAVING AN OVERALL SURFACE OFTHERMOPLASTIC MATERIAL THAT BECOMES ADHESIVE WHEN SUBJECTED TO HEAT,SAID CONTAINER COMPRISING, IN COMBINATION, A TUBULAR BODY, A TOP CLOSUREOVERLYING SAID BODY, FIRST AND SECOND PAIRS OF OPPOSED BOTTOM CLOSUREPANELS CONNECTED TO SAID BODY, SAID SECOND PAIR OF BOTTOM CLOSURE PANELSBEING TRIANGULAR IN SHAPE AND INFOLDED BETWEEN SAID BODY AND SAID FIRSTPAIR OF BOTTOM CLOSURE PANELS, TWO PAIRS OF TRIANGULAR FOLD-BACK PANELSEACH PAIR OF WHICH IS CONNECTED TO A RESPECTIVE ONE OF SAID TRIANGULARBOTTOM PANELS AND TO RESPECTIVE ONES OF SAID FIRST PAIR OF OPPOSEDBOTTOM CLOSURE PANELS, SAID FOLDBACK PANELS ALSO HAVING CUT EDGES ANDBEING FOLDED AGAINST THE INSIDE SURFACE OF SAID FIRST PAIR OF OPPOSEDBOTTOM PANELS, THE COMBINED LENGTH OF SAID FOLD-BACK PANELS ALONG SAIDOPPOSED BOTTOM PANELS OF SAID FIRST PAIR BEING GREATER THAN THE LENGTHOF THE BASE OF THE ADJOINING TRIANGULAR BOTTOM PANEL WHEREBY SAIDFOLD-BACK PANELS ARE CROWDED TOGETHER ALONG THEIR CUT EDGES UPONINFOLDING AND SEALING OF SAID BOTTOM CLOSURE PANELS.